I don't have a big list, because I've been playing a game: Avernum 5.
I have been besotted by the wooden periodic table of the elements. Amazing woodwork, amazing chemistry, fascinating samples; I have spent hours browsing this. Look! Uranium dinnerware!
The American elections are yielding a steady drip of total insanity, which is hilarious when it's not tragic. Check out the Palin as President flash game: just click around and see what happens. There's a lot to find. Or how about some blogs: the Palindrome, Teen Moms for Palin.
Another big site for addictive browsing is the tropes wiki. Despite the site name, it's not just about TV, but all media. I keep thinking that I ought to sign up to improve the list of food tropes. In another life, when I have the time.
And finally, don't forget to wash your coffee cups!